SQL - UPDATE Query

The SQL UPDATE Query is used to modify the existing records in a table.

You can use WHERE clause with UPDATE query to update selected rows otherwise all the rows would be affected.

Syntax:

The basic syntax of UPDATE query with WHERE clause is as follows:

  UPDATE table_name  SET column1 = value1, column2 = value2...., columnN = valueN  WHERE [condition];

You can combine N number of conditions using AND or OR operators.

Example:

Consider the CUSTOMERS table having the following records:

  +----+----------+-----+-----------+----------+  | ID | NAME     | AGE | ADDRESS   | SALARY   |  +----+----------+-----+-----------+----------+  |  1 | Ramesh   |  32 | Ahmedabad |  2000.00 |  |  2 | Khilan   |  25 | Delhi     |  1500.00 |  |  3 | kaushik  |  23 | Kota      |  2000.00 |  |  4 | Chaitali |  25 | Mumbai    |  6500.00 |  |  5 | Hardik   |  27 | Bhopal    |  8500.00 |  |  6 | Komal    |  22 | MP        |  4500.00 |  |  7 | Muffy    |  24 | Indore    | 10000.00 |  +----+----------+-----+-----------+----------+

Following is an example, which would update ADDRESS for a customer whose ID is 6:

  SQL> UPDATE CUSTOMERS  SET ADDRESS = 'Pune'  WHERE ID = 6;

Now, CUSTOMERS table would have the following records:

  +----+----------+-----+-----------+----------+  | ID | NAME     | AGE | ADDRESS   | SALARY   |  +----+----------+-----+-----------+----------+  |  1 | Ramesh   |  32 | Ahmedabad |  2000.00 |  |  2 | Khilan   |  25 | Delhi     |  1500.00 |  |  3 | kaushik  |  23 | Kota      |  2000.00 |  |  4 | Chaitali |  25 | Mumbai    |  6500.00 |  |  5 | Hardik   |  27 | Bhopal    |  8500.00 |  |  6 | Komal    |  22 | Pune      |  4500.00 |  |  7 | Muffy    |  24 | Indore    | 10000.00 |  +----+----------+-----+-----------+----------+

If you want to modify all ADDRESS and SALARY column values in CUSTOMERS table, you do not need to use WHERE clause and UPDATE query would be as follows:

  SQL> UPDATE CUSTOMERS  SET ADDRESS = 'Pune', SALARY = 1000.00;

Now, CUSTOMERS table would have the following records:

  +----+----------+-----+---------+---------+  | ID | NAME     | AGE | ADDRESS | SALARY  |  +----+----------+-----+---------+---------+  |  1 | Ramesh   |  32 | Pune    | 1000.00 |  |  2 | Khilan   |  25 | Pune    | 1000.00 |  |  3 | kaushik  |  23 | Pune    | 1000.00 |  |  4 | Chaitali |  25 | Pune    | 1000.00 |  |  5 | Hardik   |  27 | Pune    | 1000.00 |  |  6 | Komal    |  22 | Pune    | 1000.00 |  |  7 | Muffy    |  24 | Pune    | 1000.00 |  +----+----------+-----+---------+-------